1. Field of the Invention
The present invention relates to a playback apparatus, for recorded audio and video information, that utilizes laser light, in particular, to a recorded disk playback apparatus with a simplified loading mechanism which additionally reduces the number of motors and speed reduction mechanisms that are required.
2. Description of the Prior Art
Several years ago, there was introduced in the fields of audio and video an optical video disk in which the information on the recording disk (referred to as the disk hereafter) is reproduced by irradiating the disk with laser light. The signals are represented by variations in the amount of returned light due to diffraction by the pits on the disk surface. As for the playback apparatus itself, a front loading system is in wide use in which the loading/unloading of the disk is carried out from the front of the playback apparatus. This provides for easy operation and efficient utilization of space. In what follows, a description will be given of a prior art recorded disk playback apparatus for optical disks of the front loading type by referring to FIGS. 1 through 9.
In FIG. 2 is illustrated the configuration in which the slide table 10 for taking in and out the disk has been pulled out of the main frame 12 of the playback apparatus, while in FIG. 1 is shown the configuration in which the slide table 10 has been pushed in.
The operations of loading/unloading are illustrated in FIGS. 3 to 5.
In FIGS. 3 and 4 it is shown that the lifter 18, which acts to place the disk 14 onto the turn table 16, is installed on the slide table 10 in such a manner that it is freely movable up and down. On the turn table motor 20, the turn table 16 and the center spindle 22 for centering the disk 14 are installed so as to rotate with the turn table motor 20 as one united body.
The disk clamper 24 which moves up and down due to the turning of the support arm 28, which turns around the fulcrum 26, plays the role of clamping the disk 14 onto the turn table 16.
For loading the disk, the disk 14 is placed on the slide table 10, which is pulled out as shown by FIG. 3, and then the slide table 10 is pushed in, as shown by FIG. 4. It now becomes necessary to place the disk 14 on the turn table 16, since in this state the disk 14 is still sitting on the slide table 10. When the slide table 10 is pushed in, the lifter 18 that was supporting the disk 14 moves downward to a position which is lower than the turn table 16, leaving the disk 14 on the turn table 16. At the same time as this, the disk clamper 24, that is installed on the center stay 30, comes down to clamp the disk 14. By these actions, the disk 14 is clamped between the turn table 16 and the disk clamper 24, and the disk 14 rotates due to the rotation of the turn table motor 20.
In FIG. 5 is illustrated the condition in which the loading of the disk 14 is completed. For unloading the disk 14, it is necessary to reverse the above actions. The disk 14 that was rotating is brought to a stop. The disk clamper 24 and the lifter 18 move upward as shown by FIG. 4. The disk 14 is removed from the top of the turn table 16 to the top of the lifter 18, and the slide table 10 is pulled out as shown by FIG. 3 to allow the disk 14 to be taken out.
The mechanisms for carrying out the loading/unloading as described in the above will be illustrated in FIGS. 6 and 7.
In FIG. 6 is shown the mechanism of the loading drive motor and the construction of the disk clamper. The rotation of the loading drive motor 32 is transmitted to the pinion 44 via the belt 34, a small pulley 36, and a large pulley 38, its speed being reduced by the worm 40 and the worm wheel 42. On the rack 46 there are created long openings 48a and 48b to which are inserted in slidable fashion the posts 52a and 42b, respectively, that are installed protruding from the bottom of the chassis 50. Since the pinion 44 and the rack 46 are kept engaged between them, the rack 46 is able to move back and forth, (in the directions of the arrows in the figure) with respect to the main frame of the playback apparatus, by the rotation that is transmitted to the pinion 44. On the other hand, the disk clamper 24 moves up and down with the turning of the two arms 28a and 28b, each of which have ends supported on the sides of the chassis 50 by the pins 26a and 26b, using pins 26a and 26b as the fulcrums. On the arm 28a there is formed a sloped cam 54 which makes a direct contact with the roller 57 that is installed on the rack 46 to be freely rotatable, by means of a spring 56 which has one end attached to the arm 28b.
A U-shaped metallic fitting 58 is installed in a turntable fashion on the indentations 58a and 58b that are prepared on both sides of the chassis 50, and the branches 60a and 60b on both ends of the U-shaped fitting make contact with the rollers 62a and 62b prepared on the arms 28a and 28b, so as to have the force of the spring 56 apply equally on the two arms 28a and 28b. This helps the horizontal ascent/descent of the disk clamper 24 to be carried out correctly.
With the rotation of the motor 32 being transmitted to the pinion 44 by the above mechanism, as the rack 46 moves to the front of the main frame of the playback apparatus 12, the disk clamper 24 goes down, and as the rack 36 moves to the rear, the clamper 24 goes up.
Next, FIG. 7 shows the construction of the slide table, the lifter, and the ascent/descent cams. At the four corners of the lifter 18 there are installed cylindrical protuberances 64, and corresponding to these protuberances 64 there are formed on both inner surfaces of the slide table the guiding grooves 66 for guiding the protuberances 64 when they are moved up and down. The respective cam holes 72 in the left ascent/descent cams 68 and the right ascent/descent cam 70 engage the protuberances 64 of the lifter 18, holding the lifter 18 so it is slidable in the longitudinal direction along the inner sides of the slide table 10. The hole 76 created at the central part of the connecting rod 74 engages with the pin 78 of the slide table 10, and the pins 80a and 80b at both ends of the connecting rod 74 engage the left ascent/descent cam 68 and the right ascent/descent cam 70, respectively. On the left ascent/descent cam 68 there is prepared a post 86 for receiving the transmitted displacement motion of the rack 46 through its engagement with the protuberances 82 and 84 that are installed protrusively at the center of the rack 46.
FIGS. 8 and 9 show views from bottom of the slide table 10. In such a mechanism, when the rack 46 in FIG. 6 is shifted back and forth with respect to the main frame 12 of the playback apparatus, the left ascent/descent cam 68 is moved as shown by FIGS. 8 and 9. The displacement motion is also transmitted to the right ascent/descent cam 70 by means of the connecting rod 80. Then, it becomes possible to raise and lower the lifter 18 by maintaining the protuberances at the four corners of the lifter in simultaneous horizontal states with the help of the cam holes 72 of FIG. 7. This accomplishes the loading/unloading of the disk mentioned earlier.
However, in the prior art recorded disk playback apparatus as described in the foregoing, a motor for feeding the drive of the playback pick-up head and a speed reduction mechanism (not shown) are required separately from the motor for the loading drive 32 of the disk and the speed reduction mechanism, making it difficult to reduce the size and weight of the apparatus.
Moreover, in the prior art construction as described in the above, it is necessary to clamp the disk 14 by lowering the disk clamper 24 so that a mechanism for lifting/lowering the disk clamper 24 is required. Furthermore, it is also necessary to incorporate in the apparatus a mechanism for lifting and lowering the lifter 18, increase in the number of parts required further hindering efforts to reduce the size of the apparatus.
In addition, the slide table 10 and the lifter 18 are given separate piece constructions. Because of this, in the slide table 10 there is created an opening for letting the lifter 18 to pass through in order to lift and lower the lifter 18 with respect to the slide table 10. However, since the slide table 10 is pulled out and pushed in frequently, it has to be made strong enough so as not to be broken easily, in consideration of the situation in which an unintentional force in the up and down direction is applied to it. This leads to a weakness in that the apparatus has to be constructed by using a thick material in order to give the lifter 18 a separate piece construction and make it still strong enough not to break easily, even with a large opening in it.
Now, in FIG. 10 there is shown the prior art construction of the slide table and its locking/unlocking mechanism. In FIG. 10, the slide table 10 is shown to have a mechanism within which it is made slidable, inside the main frame 50 of the chassis, by means of the rollers and the rails (not shown).
In order to load the disk on the playback apparatus, the slide table 10 is pulled out from the front of the playback apparatus, the disk is placed on it, and then the slide table 10 is pushed in.
The slide table 10 becomes locked in this state, and the disk is placed on the turn table and is then held down by the disk clamper. The turn table then rotates, and the state in which playback is possible is reached when the rotation of the turn table attains a fixed speed of rotation. The locking plate 90 for locking the slide table 10 is supported by the pins 92a and 92b so as to be slidable in the directions represented by the arrows a and b. The locking plate 90 is energized in the direction, indicated by arrow a, by a spring 94. The unlock holding lever 96 is mounted turnably on the locking plate 90 by a pin 98. The unlock holding lever 96 is energized in the clockwise direction as seen from the top by a spring 98.
The stopper 100, which is prepared on the main frame 50 of the chassis, acts, via the unlocking lever 102, to guide the locking board 90 as it is moved to the left.
The solenoid 104 that is attached to the main frame 50 of the chassis acts as the source of the power for moving the locking board 90 in the direction of the arrow b.
On the arm 106 there are provided arm tips 106a and 106b. The tip 106a is engaged with the plunger 108 of the solenoid 104 by a pin 110. The other arm tip 106b makes direct contact with the bent portion 90a of the locking plate 90. By this arrangement, when the solenoid executes its sucking action, the locking plate 90 is moved in the direction indicated by arrow b.
The operation of the prior art mechanism as described in the above is as follows: when the locking roller 112a, of the two locking rollers 112a and 112b, of the slide table 10 starts to press the unlock holding lever 96, the unlock holding lever 96 is released from the stopper 100, the locking plate 90 slides, in the direction indicated by arrow a, under the force of the spring 94. The locking action is completed by holding down the locking rollers 112a and 112b.
To pull out the slide table 10, by operating the unloading button or the like, the solenoid 104 conducts electricity momentarily, and sucks the plunger 108.
Due to this action, the arm 106 rotates to move the locking plate 90, in the direction indicated by arrow b, and the locking rollers 90a and 90b are released.
However, in locking/unlocking mechanism according to the prior art techniques, in order to release the lock of the slide table, a solenoid with a large amount of power has to be utilized. The use of such a solenoid causes a rise in the cost, and is undesirable due to the space occupied by the solenoid from a reduction in size viewpoint. It is also disadvantageous due to the weight of the solenoid from a reduction in weight viewpoint.